Furnace



FURNACE 7 Filed July 1, 1921 4 Sheets-Sheet 1 Jay;

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N. E. MACCALLUM FURNACE Filed July 1, 1921 4 Sheets-Sheet 5 Patented Aug. 12, 1924-,

UNITED STATES PATENT orries.

NORMAN E. MAGGALLUM, F PHOENIXVILLE, PENNSYLVANIA.

FURNACE.

Application filed July 1,

oblong hearth arched over by a roof. These furnaces have generally comprised two pairs of checker chambers or regenerators, one pair being arranged adjacent each end of the hearth; means for supplying gaseous fuel and air to the hearth alternating through two sets of regenerators; and a stack adapted to be placed in communication with the hearth alternately through the two sets of regenerators. In the operation of this furnace as heretofore constructed, the gaseous fuel is conducted to the hearth, through one of a pair of regenerators, and the air is simultaneously conducted to the furnace through the other of said pair of regenerators, the products of combustion or exhaust gases making their exit through a second pair of regenerators on the opposite side of the hearth to the stack.

At frequent intervals, the direction of gaseous fuel and air over the hearth is reversed, so that the incoming air and fuel between a pair of regenerators heated, during the preceding period, by the exhaust gases may be preheated in their passage to the hearth. These reversals of the direction of the air and gaseous fuel and of the waste products of combustion are effected fre quently and regularly until the charge is ready to tap. This reversal of the air and fuel and of the waste gases of combustion is effected by a pair of valves which are manipulated in any suitable manner from time to time by any suitable means.

Heretofore it has been considered advisable, in delivering the gaseous fuel and the air to the hearth, to arrange thev ports, through which said air and gas are delivered, at different elevations, the air ports being above the gas port, and this relative arrangement of the said ports necessitates 1921. Serial No. 481,752,

the construction within the furnace, and below the roof thereof, of walls, partitions, or arches between the gas port and the air ports, where said walls or arches are subjected to the extreme heat-and chemical action of the v outgoing gases and the positioning the end 'of the roof Well above said ports and arches or walls or partitions.

A furnace of the character above described will operate with substantially equal efliciency when the gas and air ports are located at the same distance from the top of the furnace, and by placing the said ports at the same level I am able to dispense with all interior arches in the port ends of the furnace. Such interior arches frequently break down, and require repair, in the ordinary steel furnace, on account of the intense heat to which they are subjected by the outgoing gases.

The objects of my invention are to provide a furnace in which the ports for the fuel or gas and air respectively are located in substantially the same plane or at the same level above the hearth; to dispense with interior arches or partitions between the air ports and the gas port; to drop the ends of the furnace to a lower level; thatis to say, to a position in line with the top wall of the gas port of the former type of furnace; and to provide a free passage distinct from the reversing valve passages for the gases of combustion from the checkers or regenerators to the stack, to increase the draft through the furnace.

Other objects of my invention will appear in the specification and claims below.

In the drawings forming a part of this specification and in which the same reference characters are used throughout the various views: I

Fig. l is a horizontal sectional view through the major portion of the furnace, but below the hearth, showing the location of the ducts or passages for the fuel, air and waste gases, the valves for reversing the direction of the flow of the fuel through the furnace and the new passage for the gases of combustion and waste gases from the checkers or regenerators to the stack.

Fig. 2is a diagrammatic view of the re versing valves for the air and gas, indicating their relative adjustmentswhen the air Fig. is a horizontal sectional view of an .end of the furnace taken on the line 55 of Fi ni,

Fig. 6 1s a vertical sectional view on the line 66 of Fig. 4.

Figs. 7 and 8 are views similar to Figs. 5 and 6 respectively, of a modified construction with the vertical walls between the ports removed; and

9 is a perspective view of the cap of -'one of the reversing valves.

. -One embodiment of my invention comprises an open hearth furnace including the usual hearth 1 provided with aroof 2, the ends 33 ofrwhich lie immediately above and form the top walls of the air and gas flues. At each end of the furnace are two ports 4-4 for the air and hereafter termed the air ports and on each end of the furnace is a gas port 5 situated inthe same plane or at the same level as that of the air ports and between them. The ends of the roof 2 of .the furnace over the hearth slope downwardly towards the ends thereof and lie in the plane ofand form the top wall of the air and gas. flues Vertical walls 66 may be placed between the gas port 5 and the air ports 4-4 and when employed they are preferably made of highly refractory material, such for instance, as a stack of metallic containers filled with basic material as described in my United States Letters Patent, No. 1,106,725,

. dated August 11, 1914. I may, however, en-

tirely omit these walls 66, as will be referred again to below. i 'Adjacent each end of the furnace and preferably below the hearth are a pair of regenerators or checker chambers 7, 8 and 9, 10, the interior of each being preferably sub-divided into a plurality of passages by bricks 11 or checkers in the ordinary way.

The smaller regenerator chambers 7 and 9 are the chambers'through which the gaseous fuel passes to the hearth, and the larger regenerator chambers 8 and are those through which the air passes to the hearth. The chamber 7 communicates with the hearth through the port 5 'onone side of the hearth and the chamber 9 communicates with the hearth through the port 5 on the other side of the hearth. Similarly, the regenerator chamber 8 communicates with the hearth through theports 66 on the opposite side of the hearth, and the chamber 10 through the ports 6-6 with the said opposite side of the hearth. The gaseous fuel is conducted to the hearth through a pipe 11, from which is a passage 12 to a port 13 of the gas control valve 14. The cap 14 of the valve 14 is hollow and is preferably divided diametrically vertically by a wall or partition 15 so that the port 13 may be put into communication with the flue or passage 16 leading to the gas regenerator chamber 7, or, by turning the valve through 90 the port 13 may be put into communication with the flue or passage 17 communicating with the other gas regenerator chamber 9. The four ports leading into the valve 14 are port 13 from the gas supply 11, port 18 to the flue 17 port 19 to the flue 20 leading to the stack 21, and port 22 leading to the passage 16 of the gas regenerator chamber 7.

The air valve 23 is also provided with the four ports, namely, port 24 leading to the flue 25 communicating with the air regenerator chamber 10, port 26 communicating with the passage and 31 forming the air supply duct, port 27 leading to the passage '28 communicating with the air regenerator chamber 8 and port 29 communicating with the stack flue 21 through the passage 20. The top 23 of this valve is precisely like the cap 14 of the gas supply valve 14.

' In Figs. 2 and 3 are diagrammatically shown the two relative positions of the valves 14 and 23. In Fig. 2 the air from the ducts 30 and 31 is passing through the ports 26 and 27 to passage 28 and thence to the air regenerator chamber 8, and the gaseous fuel is passing through the ports 13 and 22 to the chamber 7. In Fig. 3 the air from ducts 30 and 31 is passing to the chamber 10 through the ports 26, and 24, and the passage 25 and the gas is passing through the ports 13 and 18 into the chamber 9.

Leading from the regenerator chamber 8 is a duct 32 communicating through pi e with a passage 20 leading to the st-ac 21, and similarly, a duct 34 from chamber 10 communicates through said pipe 33 with the passage 20 to the stack. In the passage 32 is a valve 35, preferably closing by gravity and lifted by a chain 36 passing over a pulley 37, said chain being wrapped partly around the cap 23 of the air valve 23, and in the passage 34 is a like valve 37 similarly lifted from a closed position by a chain 38 passing over a pulley 39, wrapped around the said cap 23 of the said air valve 23, but in the other direction. When, therefore, the cap 23 of the valve 23 is turned in one di rection, it will open one valve and close the other and when turned in the other direction it will reversely open and close the valves and 37.

' The operation of my improved furnace is as follows: The valves 14 and 23 being set in the manner indicated in Fig. 2, the

gas entering the port 13 travels longitudinally of the valve 14 to the cap 14 and thence downwardly through the port 22, passage 16 and checker chamber 7 to gas port 5 on the left hand end of the furnace, as shown in Fig. 4 and thence over the hearth 1. Simultaneously, air is admitted through the .air ducts 30 and 31 to the port- 26, then upwardly through the valve to cap 23, and then downwardly through the port 27, through the passage 28 and the checker chamberS to the ports 4-4 on the left hand side of the furnace shown in Fig. 4. The air and gas here ignite and sweep over K the charge on the hearth. The products of combustion or spent gases, as in the ordinary operation of this type of furnace, may pass through the ports 44, and 5 0n the right hand end of the furnace as shown in Fig. 4 and thence through the checker chambers 9 and 10 heating them to a high temperature. From the chamber 10 the products of combustion may pass through passage 25 up through the port 24 of valve 23 down through the port 29 to the passage 20 and thence to the stack 21. Similarly, the gases of combustion may pass through the checker chamber 9, through the flue 17, through the port 18 of the valve 14, thence downwardly through the port 19 of valve 14 to the flue 20 and thence to the stack 21.

The passage of all of the products of combustion through the tortuous passages provided by the valves 14 and 23 tends, however, to check or lessen the draft through the furnace to the stack. I have found that the draft through the furnace may be considerably increased by providing a passage from the larger checker chamber 10 directly to the stack, by passage 34 and valve 37' and duct 33 to thepassage 20 leading to flue 21. When the valve 23 is in the position shown in Fig. 1, the valve 37 is in its raised position to open the passage 34 to the stack.

After the furnace has been operated in this manner sufiiciently long to heat up the checker chambers 9 and 10 to the required extent, the direction of thefuel through the furnace is then changed. The valves 14 and 23 are set in the position shown in Fig. 3. Thereupon gas admitted through the port 13 passes through port 18 and passage 17 through the checker chamber 9 and through port 5 to the hearth. The air from the ducts 30 and 31 passes through port 26 and port 24, through passage 25, and checker chamber 10 to ports 44 and thence to the hearth. Similarly, the products of combustion pass out through the opposite ports 4, 4, chamber 8, passage 28 to port 27, thence through port 29 and passage 20 to the stack 21, and they also pass through the port 5, checker chamber 7, passage 16, port 22 to port 19 to passage 20 to stack, but the greater part of the products of combustion will pass from chamber 8, through the open valve 35 to duct 33 and passage 20 to stack 21, instead of being obliged to passthe tortuous passages of the reversing valves 23 and 14.

In operating my improved furnace in the manner above described, it will be seen that the air and the gas enter the furnace'on the same level through the ports 4, 4 and 5; that the easily broken down interior arches or partitions between the air and gas ports are eliminated. In constructing by improved furnace the ends 3, 3 are lower than the middle of the hearth and the roof forms the top wall. of both the air and gas ports. But when so constructed the roof forming the top walls of the ports, is not subject to so great a destructive action, because it is cooled, to a considerable extent, by the surrounding atmosphere.

By my invention I may remove entirely the walls 66, shown in Figs. 1 to 6 without otherwise changing the structure. It may be desirable in treating some steels, to fix the point where the ignition begins more remote from the ends of the hearth than it is in such a construction as I have already described. In Figs. 1 to 8, I have shown such a modification of my invention. In this construction the air is delivered through the ports 4, 4 and the gas through port 5 as before, but immediately upon their exit therefrom they mix and ignite considerably back of the edge of the ends of the hearth 1. The roof still forms the top wall of the ports, all interior arches are obviated, and the air and gas enter the furnace on the same level with respect to the hearth.

It is to be understood that my said invention is not to be construed as limited to the precise details above described, as many changes, both in the construction and operation of the furnace, may be made without departing from the spirit and scope of my invention. These open hearth furnaces difier in minor details from each other, dependent upon the locality where they are situated, andv the kind of steel which is to be treated therein and such furnaces may be readily changed to embody my invention. All such furnaces may be provided with an auxiliary passage to the stack around the reversing valves so that most of the products of combustion are not required to traverse the tortuous passages through the reversing valves, and such auxiliary passages may be provided with anysuitablevalves or dampers, preferably operated by the air and fuel reversing valves. Furnaces now in use may be changed and modified and reconstructed so as to provide air and gas or fuel ports leading to the hearth, all disposed in the same plane or at substantially the same level above the hearth, provided the roof of the furnace be lowered to form the top walls of the air-and fuel ports. Such changes and modifications are fully within the aim and scoperof my invention. 7 Having thus described my invention, I claim and desire to protect by Letters Patent of the United States:

1. V In a steel furnace of the reversible open hearth type,'and provided with a hearth, regenerator chambers, reversing valves and a 21* stack, the combination therewith of an auxstack, the combination therewith of an auxiliary passage from the regenerator chambers to the stack, a valve or damper in said auxiliary passage and means operated by said reversing valves to open and close the.

same.

, '3. In a steel furnace of the reversible open hearth type, and provided with a hearth,

regenerator chambers, reversing valves and a stack, the combination therewith of an aux- 1l1ary passage from the regenerator chambers to the stack, a valve or damper in said 11 auxiliary passage and means to open and close said last-mentioned valve by said reversing valves.

4. In a steel furnace of the reversible open hearth type provided with a hearth, regenerator chambers. reversing valves, a stack, and a roof, the combination therewith of air and gaseous fuelports located on o posite ends of said hearth and at substantia ly the same level above the hearth, said roof forming the top wall of said ports, and an auxiliary passage for the outgoing gases connecting said regenerator chambers With said stack and independent of the passage through said reversing valves, and means in said auxiliary passage and operated by said reversing valves to control the flow of said outgoing gases therethrough.

In witness whereof, I have hereunto set my hand this 30th day of June, 1921.

NORMAN E. MACOALLUM. 

